Byron Field sits in Big Horn County, Wyoming, in the northern Bighorn Basin near the towns of Byron and Cowley. It is one of the oldest oil producers in the basin — old enough that Wyoming’s state geologist was already describing it as long established in 1917, when a small refinery at Cowley was running its shallow production. What makes Byron notable now is not its age but its engineering: Marathon Oil later ran the Tensleep-Embar Unit as the Bighorn Basin’s first full-field commercial tertiary flood, using polymer rather than plain water.
Byron belongs to the first generation of Bighorn Basin fields, drilled on obvious surface anticlines by operators who could see folded rock from the road. Wyoming’s 1917 state geological bulletin already treated Byron as an established producer, noting that a small refinery at nearby Cowley had been running for close to a decade on modest output from shallow wells. Because that early record is fragmentary, the field’s exact discovery date is reported differently in different sources, and the roster year should be read as an approximation rather than as a documented completion.
Deeper drilling redefined the field, as it did across the basin. The Pennsylvanian Tensleep sandstone and the Permian Phosphoria — long called the Embar in Wyoming usage — proved to be the real reservoirs, far more substantial than the shallow sands that supported the Cowley refinery. Unitization followed, organizing the Tensleep and Embar into a single engineered reservoir so that injection could be run across lease lines. That step is the reason a field of Byron’s vintage still had a technical future rather than a slow slide into abandonment.
Marathon Oil then made Byron a proving ground. The company initiated a polymer waterflood in the Byron Field Tensleep-Embar Unit, described in the technical literature as the first full-field commercial tertiary flood in the Bighorn Basin, injecting a substantial fraction of a pore volume of polymer solution. Polymer thickens injected water so it sweeps more evenly through rock of uneven permeability instead of running through the best streaks. Operatorship of the northern Bighorn fields has moved repeatedly since, and current operatorship should be confirmed from your division order.
Byron is an anticlinal field on the northern rim of the Bighorn Basin, where Paleozoic reservoirs sit at shallow enough depth to have been reached by early drilling. The productive column runs from Cretaceous Frontier sands down into the Permian Phosphoria and the Pennsylvanian Tensleep, the eolian sandstone that carries most of the basin’s oil. Tensleep permeability is famously uneven, varying between cross-bedded units, and that heterogeneity is precisely why a polymer flood — designed to sweep unevenly permeable rock more uniformly than water alone — was tested here rather than somewhere simpler.
Byron’s recovery history moves through all three stages. Primary production drained the shallow pays for decades; waterflooding of the unitized Tensleep-Embar restored pressure and swept oil toward producers; and Marathon’s polymer flood added a tertiary phase aimed at the oil that plain waterflooding bypasses. Polymer raises the viscosity of injected water so it advances as a more even front through variable rock. For a mineral owner the effect of that sequence is duration: a century-old field that still pays, at low rates, because each stage of investment extended the paying life of the same reservoir.
Byron interests are classic old-Wyoming royalties — small monthly amounts, very long payment histories, and title that has passed through several generations of heirs, often with unprobated links in the chain. The production itself is stripper-grade and flood-supported, so it declines slowly rather than steeply, which makes it valuable for reasons a simple income multiple does not capture. Buyers vary widely in how they treat interests like this. We buy minerals and royalties in Big Horn County and provide free written offers.
County-level well data, production charts, and selling guides for the counties this field spans:
It is a form of enhanced recovery in which a water-soluble polymer is added to injected water to thicken it. The thicker fluid sweeps more evenly through rock of uneven permeability, reaching oil that ordinary waterflooding channels past. Marathon ran one at Byron in the Tensleep-Embar Unit.
The early record is imprecise. Wyoming’s 1917 state geological bulletin already described Byron as one of the oldest producers in the Bighorn Basin, with a refinery at Cowley running for years on its shallow wells, so the field predates the discovery years commonly listed for it.
Frequently more than owners expect. Flood-supported Bighorn Basin production declines very slowly, so a small check can represent a long remaining stream, and the value of the underlying minerals is separate from current income. Send a check stub or legal description and we will put a written number on it.